Solar control glazing

ABSTRACT

A vehicle glazing comprises a pane of tinted glass, tinted by at least 1.0 to 1.8% wt. of total iron, having a low emissivity coating on its interior surface. The coating has an emissivity from 0.05 to 0.4 and may include a transparent conductive oxide (and optionally a dopant), or a metal layer and at least one dielectric layer. The glass is preferably toughened glass. According to another aspect, a laminated glazing includes two plies of glass, with a sheet of interlayer material laminated between the two glass plies, and wherein at least one ply of glass or the sheet of interlayer material is body tinted. The glazing has a low emissivity coating on its interior surface, the inner ply may be clear glass or tinted glass, and the interlayer material may be clear PVB or tinted PVB, and may further be infra-red reflecting. Either of the glazings may be used as a roof or other vehicle glazing.

This application is a divisional of U.S. application Ser. No. 10/563,917having a filing date of Jan. 10, 2006, which is a U.S. national stageapplication based on International Application No. PCT/GB20004/002997having a filing date of Jul. 9, 2004 and which claims priority to U.K.Application No. 0316248.4 filed on Jul. 11, 2003 and U.K. ApplicationNo. 0413651.1 filed on Jun. 18, 2004, the entire content of all four ofwhich is incorporated herein by reference.

TECHNOLOGICAL FIELD

The present invention relates to a vehicle glazing, especially to asolar control vehicle glazing, which is coated and tinted, and which mayfurther be incorporated into a laminated glazing also for use in avehicle.

BACKGROUND DISCUSSION

Tinted glazings having a coating on one of their surfaces to impartsolar control properties to said glazing are known, particularlyglazings of this type which are intended for architectural use. One suchglazing is described in EP 1 004 550 A1 and is referred to as aheat-reflecting glass suitable for use in windows of buildings,especially in double glazing units. The glass substrate is coated withat least one layer of a film mainly comprising silicon. The resultantheat-reflecting glass thus has low visible light reflectance and agreen, bronze or grey reflected colour tone.

U.S. Pat. No. 6,538,192 B1 describes a tinted, coated glazing for use inthe roof of a vehicle. It particularly describes a laminated roofglazing comprising an outer pane of “extra clear” glass (typicallyhaving a total iron content less than 0.1% by weight), a laminatinginterlayer accommodating an array of photovoltaic cells which cover onlya portion of said glazing, and an inner pane of tinted (and optionallycoated) glass. The outer pane of extra clear glass has maximized energytransmission to allow the proper functioning of the photovoltaic cells,whilst the inner pane is tinted, and optionally coated with an athermiccoating, to specifically reduce the maximized energy transmissionthrough the portion of the glazing not covered by the photovoltaicarray, thereby increasing vehicle passenger comfort. The optionalcoating is provided on the surface of the inner pane of tinted glassfacing into the laminate such that it is in contact with the interlayer.In this position, the coating is devoid of contact with the environmentexternal to the glazing, and is protected from degradation and abrasion.

The laminated roof glazing described in U.S. Pat. No. 6,538,192 B1 has aspecific purpose; namely to reduce the energy drain on a vehicle's powersource by using, and aptly locating, photovoltaic cells in the glazing.The purpose for which the laminated glazing is intended thereforedictates the requirements for a high energy transmission (i.e. greaterthan 80%) outer pane of glass, and a tinted inner pane of glass whichthereby compensates for the increased energy transmission (compared tostandard clear glass) of the outer glass.

It would be desirable to provide a vehicle glazing that reduces theamount of energy, especially heat energy, in the form of incident solarradiation which would otherwise be transmitted through said glazing.

It would be especially desirable to provide a laminated glazing for usein a vehicle, that reduces the amount of energy, especially heat energy,in the form of incident solar radiation which would otherwise betransmitted through said glazing.

SUMMARY

We have found that such vehicle glazings may be achieved by providing apane of glass which is tinted by use of at least iron, and a lowemissivity coating on one of the surfaces of the glazing.

According to a first aspect of the present invention there is provided avehicle glazing comprising a pane of tinted glass, said glass having acolourant portion including 1.0 to 1.8% (by weight of the glass) oftotal iron (calculated as Fe₂O₃), 100 to 270 ppm by weight of cobaltoxide (calculated as CO₃O₄) and selenium (calculated as Se) in an amountless than 20 ppm by weight, and a low emissivity coating on the interiorsurface of the pane. By “the interior surface” of the pane of glass ismeant the surface of that pane which would form an interior surface ofthe vehicle into which the glazing may be fitted.

The total iron content of the glass plays an important role indetermining both the level of absorption of incident energy achieved bythe glazing, and also the overall tint of the glazing. The total ironcontent is more preferably in the range from 1.3 to 1.6% by weight. Thetint exhibited by the glazing is preferably a grey, blue or green tint(although a bronze tint is also envisaged), and is further preferably adark tint (i.e. the glazing has a visible light transmission of 50% orless).

Cobalt oxide serves to reduce the visible light transmission of theglass in which it is present, and is more preferably included in theglass in the range from 150 to 230 ppm by weight. Selenium aidsachievement of a bronze to grey tone when in existence with cobalt.

The coating usually includes a metal or metal oxide layer and, in thelatter case, the layer may also include a dopant material, for example,fluorine or antimony. A number of low emissivity coatings are known inthe art, any of which may be used in accordance with the presentinvention. The emissivity of a particular coating refers to the tendencyof that coating to radiate energy. Thus a low emissivity coating is apoor thermal radiator (compared to a blackbody entity, which is aperfect radiator and is defined as having an emissivity of unity). Lowemissivity coatings may be provided as one of two principal types:“hard” or “pyrolytic” coatings and off-line coatings which are normallyproduced by sputtering, and are commonly softer than typical pyrolyticcoatings.

A hard coating may be deposited in an “on-line” process, in which thecoating is pyrolytically deposited onto the surface of float glassduring its formation, in known manner, for example by use of a chemicalvapour deposition process. Generally, deposition occurs in the region ofa float line where the glass ribbon is at a temperature of between 400and 760° C.; glass of this temperature may be found towards the exit ofthe tin bath, in the lehr gap (i.e. in the gap between the tin bath andthe annealing lehr) and in the hot-end of the annealing lehr. As theglass is fully annealed (i.e. sequentially cooled from its highertemperature state to room temperature), the coating is cured, thus thecoating species which initially fused to the glass surface via pyrolysiseffectively forms part of the final glass product. The coated side ofthe glass may be further subjected to a polishing process to reduce themicroscopic rugosity of the coated surface to produce a glass that maybe more easily handled.

An off-line coating is one that is deposited onto the surface of a pieceof glass subsequent to complete manufacture of the glass, i.e. in aseparate process from the float process. Hence the deposition process isan “off-line” process. Off-line coatings include sputtered coatingswhich are deposited, for example by use of a magnetic sputteringtechnique under vacuum conditions.

The low emissivity coating present on the glass used in the glazing ofthe present invention will normally be such that when used on 3 mm clearfloat glass, the coated glass has an emissivity in the range from 0.05to 0.45; the actual value being measured according to EN 12898 (apublished standard of the European Association of Flat GlassManufacturers); coatings resulting (when used in 3 mm clear float glass)in an emissivity less than 0.3 are preferred. Hard coatings generallyhave emissivities greater than 0.15 (and preferably less than 0.2),whilst off-line coatings, normally sputtered coatings, generally haveemissivities greater than 0.05 (and preferably less than 0.1). In bothcases, the emissivities may be compared with the assumed normalemissivity of clear uncoated glass, which has a value of around 0.89.

A hard (or pyrolytic) low emissivity coating may comprise a single layerof metal oxide, which is preferably a transparent conductive oxide.Oxides of metals such as tin, zinc, indium, tungsten and molybdenum maybe comprised in the single layer of metal oxide. Usually the coatingfurther comprises a dopant, for example fluorine, chlorine, antimony,tin, aluminum, tantalum, niobium, indium or gallium, so that coatingssuch as fluorine-doped tin oxide and tin-doped indium oxide may result.Typically, such coatings are provided with an underlayer e.g. comprisinga silicon oxide or silicon oxynitride which serves either as a barrierto control migration of alkali metal ions from the glass and/or as acolour suppressing layer to suppress iridescent reflection coloursresulting from variations in thickness of the low emissivity layer.

Off-line low emissivity coating typically comprise a multilayer coatingstack which normally includes a metal layer (or a conductive metalcompound) and at least one dielectric layer. The multilayer stackstructure may be repeated to further enhance the emissivity of thecoating. Amongst other similar metals, silver, gold, copper, nickel andchromium may be used as the metal layer in a multilayer stack; indiumoxide, antimony oxide or the like may be used as the conductive metalcompound. Coatings comprising one or two layers of silver interleavedbetween layers of a dielectric such as an oxide of silicon, aluminum,titanium, vanadium, tin or zinc are typical multilayer stacks. Generallythe one or more layers from which the coating is formed are of the orderof tens of nanometers in thickness.

The glass used in the glazing of the present invention may be flat or itmay be curved, and in addition it may be toughened, for example bythermal or chemical tempering. When the glass is subjected to a heattreatment process, for example tempering or bending, this may be beforeor after deposition of the low emissivity coating. Should the heattreatment process occur after deposition of the coating, the coatingshould be one which is not degraded by the exposure to elevatedtemperature.

Usually the glass will be in a thickness of 8 mm or less (yet greaterthan 1.5 mm), however a thickness in the range from 2 mm to 6 mm ispreferred.

The pane of tinted glass used in the glazing of the present inventiongenerally has a clear base glass composition in the range (by weight):

SiO₂ 68-75% Al₂O₃  0-5% Na₂O 10-18% K₂O  0-5% MgO  0-10% CaO  5-15% SO₃ 0-2%The glass may also contain other additives, for example, refining aids,which would normally be present in an amount of up to 2%.

Normally the glass used in the glazing has a ferrous oxide content(calculated as FeO) in the range 0.05 to 1.6% by weight. Absorption oftotal energy that is incident on the glazing (especially that which isincident on the uncoated surface of the glazing), in particular heatenergy in the form of IR radiation, may be achieved by regulating theferrous oxide content of the glazing. Preferably the ferrous oxidecontent is greater than 0.4% by weight, further preferably greater than0.8% by weight and most preferably greater than 1.2% by weight. Thehigher the ferrous oxide content of the glass, the more total energy isabsorbed by the glass, particularly near infra red (“NIR”) radiation,which is IR radiation of comparatively short wavelength and thus highenergy. The relationship between radiation of a specific wavelength (λ)and its corresponding energy (E) is given by:

$E = \frac{hc}{\lambda}$where h is Planck's constant and c is the speed of light.

Solar energy absorbed by the glass, however, does not remain absorbed;it is re-radiated by the glass over a different wavelength range thanthat of the incident energy and in all directions, thus at least someradiation is directed away from the low emissivity coating whilst someis directed towards it. The re-radiated energy includes an IR componentof longer wavelength and thus lower energy than the incident NIRcomponent. The low emissivity coating is a poor radiator of longwavelength IR radiation and therefore reduces the total amount of energypassing into a vehicle glazed with a solar control glazing of thepresent invention.

Advantageously, the glass used in the glazing has a nickel content(calculated as NiO) in the range up to 500 ppm, and preferably it isgreater than 55 ppm, further preferably greater than 100 ppm and mostpreferably greater than 200 ppm. Nickel is an ingredient that is addedto a glass composition to achieve a grey to brown colour tone.

Normally the glazing has a visible light transmission of 50% or less.The visible light transmission of a glazing is measured using C.I.E.Illuminant A (“LT_(A)”) over the wavelength range 380 nm to 780 nm at 5nm intervals from the uncoated side of the glazing. The darker the tintof the glazing however, the less visible light is transmitted;transmission of 36% or less, still less 28%, and further 20% or less, isthus preferred. In Europe, legislation dictates that a vehiclewindscreen must have not less than 75% visible light transmission(whereas legislation in the United States requires not less than 70%).Front passenger door glasses in both Europe and the United States arerequired to have not less than 70% visible light transmission; all othervehicle glass (for example a backlight or a sunroof) may have less than70%. Thus a glazing according to the first aspect of the presentinvention finds use as a rear passenger door glass, a backlight glassand a rooflight glass, but not as a front passenger door glass nor as awindscreen.

The glazing preferably has a transmitted energy of 30% or less, whenmeasured at Air Mass 2, ISO 9050. Further preferably the glazing has atransmitted energy of less than 20% and most preferably less than 10%.Transmitted energy (“TE”), also known as direct solar heat transmission(“DSHT”) is measured at Air Mass 2 (simulating rays from the sunincident at an angle of 30° to the horizontal) over the wavelength range350 to 2100 nm at 50 nm intervals. The low emissivity coating appears tobe successful in suppressing the re-radiated energy, especially lowerenergy IR radiation (in addition to incident lower energy IR radiation),thereby reducing the amount of heat transmitted through said glazing.

Absorption of higher energy IR radiation followed by at least partialreduction of re-radiated lower energy IR radiation by the glazing isespecially desirable to vehicle manufacturers in our current commercialclimate. Achievement of superior vehicle passenger comfort, for exampleby minimizing the heat gain in the interior of a vehicle, and reduceddemand on the resources of a vehicle, for example by reducing the needto use air-conditioning systems and the like, is a high priority fortoday's vehicle manufacturers.

As discussed earlier, the low emissivity coating used in the presentinvention is provided on the interior surface of the pane of tintedglass, in which position it may reduce the level of IR radiation fromthe sun that passes through the glazing (including the re-radiation oflonger wavelength radiation that is the direct result of absorption ofshorter wavelength IR radiation that is incident on the uncoated surfaceof said glazing). This effect is likely to have most utility duringsummer months when the amount of solar radiation that is incident on aglazing will usually be at its greatest.

However, the coated, tinted glazing of the present invention hasadditional benefits. During winter months in particular, when heating ofthe interior of a vehicle is necessary, for example to de-mist thewindows of the vehicle, the low emissivity coating (which is on thesurface of the glazing facing into the vehicle) may also inhibit theescape of heat radiation from inside the vehicle to the environmentexternal to the vehicle. Minimizing the amount of heat loss from avehicle may serve to reduce the “cold-shoulder effect”. This effectessentially characterizes the localized coolness in temperature that maybe felt by a passenger in a vehicle positioned close to a window, mostoften a side glazing. The cold-shoulder effect is a result of avehicle's tendency to lose heat to the outside world, particularly viait's windows and especially on a cold day. A low emissivity coating mayreduce this heat loss by reflecting longer wavelength (lower energy) IRradiation back into the vehicle, where it may heat the localized coolair close to the windows.

The advantages or the invention may be achieved with a wider range oftinted glass compositions, or indeed using a tinted interlayer withclear and/or tinted glass plies, and a laminated construction.

According to a second aspect of the invention, there is provided alaminated glazing, for use in a vehicle, comprising two plies of glasswith a sheet of interlayer laminated therebetween, wherein at least oneply of glass or the sheet of interlayer material is body tinted, and alow emissivity coating on the interior surface of the glazing.

The vehicle glazing according to the invention may be a windscreen,sidelight or backlight, but the constructions according to the inventionare particularly useful for use in rooflights (roof glazings) which areclearly subject to more intense solar radiation when the suns heat ismost intense (i.e. when it is highest in the sky), and which may belocated very close to the driver and passenger's persons.

Surprisingly, the use of a low emissivity coating is not found, to leadto an unacceptable build up of heat trapped in the vehicle; indeed withmodern vehicles, equipped with air conditioning, this is unlikely to bea problem and, with or without air conditioning, is much lesssignificant than the discomfort which results from high levels ofthermal radiation transmitted through or re-radiated by the glazing ontothe vehicle occupants.

According to one preferred aspect of the present invention a laminatedglazing, for use in a vehicle, comprises a ply of tinted glass, saidglass having a colourant portion including 0.5 to 4.0% (by weight of theglass) of total iron (calculated as Fe₂O₃), a further ply of glass and asheet of interlayer material laminated therebetween, and a lowemissivity coating on the interior surface of the glazing.

According to a further preferred aspect of the present a laminatedglazing, for use in a vehicle, comprises an outer ply of glass, an innerply of glass and a sheet of body-tinted interlayer material laminatedtherebetween, and a low emissivity coating on the interior surface ofthe glazing.

By “the interior surface” of the laminated glazing is meant the exposedsurface of said glazing which faces into a vehicle into which theglazing may be fitted (i.e. the external surface of the inner ply). Ifconventional surface-numbering terminology is used, wherein the surfaceof the laminate which contacts the environment external to a vehicle isknown as surface 1 and the surface which contacts the internalenvironment is known as surface 4, then the coating is supported onsurface 4 (the performance of a low emissivity coating is currently muchbetter on surface 4 than it is on either surface 2 or surface 3).

Typically the ply of tinted glass is the outer ply of the laminate (withrespect to the interior of a vehicle into the glazing may be fitted) andthe further ply of glass, which may be clear glass or tinted glass, isthe inner ply, although the reverse situation is also possible.

Such glazing is optimally provided in a thickness of 10 mm or less (yetgreater than 3 mm), however a thickness in the range from 4 mm to 7 mmis preferred. Furthermore, each ply comprised in the laminate isadvantageously of thickness in the range from 1.5 mm to 5 mm, although 2mm to 3.5 mm is preferred.

The sheet of interlayer material is often a sheet of transparentplastic, for example polyvinylbutyral or such other suitable laminatingmaterial, and is ordinarily provided in a thickness of 0.76 mm.Alternatively the sheet of interlayer material may be tinted to have anoptimum visible light transmission of 35% or less, preferably 18% orless. Furthermore, the sheet of interlayer material may absorb infra-redradiation, for example when it comprises tin-doped indium oxide. Bydescribing a sheet of interlayer material as being “infra-red absorbing”it is meant that when such a sheet (in 0.76 mm thickness) is interleavedbetween two pieces of clear glass (each of 2.1 mm thickness), theresulting laminate has a selectivity greater than 0.5 and preferablygreater than 1, where the “selectivity” is calculated by dividing thepercentage visible light transmission by the percentage total energy,i.e. LT_(A)/TE, each measured for the laminate.

The total iron content of the ply of tinted glass may preferably be inthe range from (in percentages by weight of the glass) 0.8 to 2.0,further preferably from 1.0 to 1.8 and most preferably from 1.3 to 1.6.The ply of tinted glass may also include other colourant components, forexample one or more of cobalt oxide (calculated as CO₃O₄) in the rangefrom 5 to 350 ppm by weight of the glass (preferably 40 to 320, morepreferably 100 to 270 and most preferably 150 to 230), nickel oxide(calculated as NiO) in an amount up to 500 ppm by weight of the glass(preferably greater than 55, more preferably greater than 100 and mostpreferably greater than 200) and selenium in an amount up to 70 ppm byweight of the glass (preferably less than 55, more preferably less than35 and most preferably less than 20).

The further ply of glass, on a surface of which the low emissivitycoating is provided, may be clear glass (“Option A”) whose compositionmay include, for example (by weight), 72.1% SiO₂, 1.1% Al₂O₃, 13.5%Na₂O, 0.6% K₂O, 8.5% CaO, 3.9% MgO, 0.2% SO₃ and optionally up to 0.2%Fe₂O₃ (preferably less than 0.15%), or it may be tinted glass (“OptionB”) which has a colourant portion including 0.5 to 4.0% (by weight ofthe glass) of total iron (calculated as Fe₂O₃), 0.05 to 1.6% by weightof ferrous oxide (calculated as FeO), 5 to 350 ppm by weight of cobaltoxide (calculated as CO₃O₄), a visible light transmission of 75% or lessand a transmitted energy of 45% or less at 2.1 mm.

The total iron content of the further ply of glass, when tinted, ispreferably in the range (% by weight) from 0.8 to 2.0, furtherpreferably from 1.0 to 1.8 and most preferably from 1.3 to 1.6.Similarly, the cobalt content is preferably in the range from 40 to 320ppm, further preferably from 100 to 270 ppm and most preferably from 150to 230 ppm. Ordinarily, if tinted, the further ply of glass may be grey,blue or green tinted, or possibly even bronze tinted glass. The ferrousoxide content of the further ply of glass is typically greater than 0.4%by weight, preferably greater than 0.8% by weight and more preferablygreater than 1.2% by weight.

Usually the further ply of glass has a visible light transmission of 55%or less, although 36% or less, and still further 20% or less, ispreferred, whilst the transmitted energy is advantageously less than30%, and furthermore less than 21%.

The laminated glazing preferably has a visible light transmission of 35%or less, further preferably of 18% or less and most preferably of 10% orless. Advantageously, the laminated glazing has a transmitted energy of20% of less. Of further advantage is transmitted energy of 15% or less,and further still, of 11% or less.

Further alternatively the further ply of glass of the laminated glazingmay be tinted glass (“Option C”) which has a colourant portion including0.4 to 4.0% (by weight of the glass) of total iron (calculated asFe₂O₃), 0.05 to 1.6% by weight of ferrous oxide (calculated as FeO), anda visible light transmission of 82% or less and a transmitted energy ofless than 60% when measured at a glass thickness of 3.9 mm (the visiblelight transmission is 88% or less and the transmitted energy 72% or lesswhen measured at a glass thickness of 2.1 mm).

The total iron content of such a tinted ply of glass is preferably inthe range (expressed as percentage by weight) from 0.45 to 2.0, furtherpreferably from 0.5 to 1.5 and most preferably from 0.58 to 1.1. Theferrous oxide content (expressed as FeO) is preferably greater than0.07%, further preferably greater than 0.09% and most preferably greaterthan 0.1%.

Typically, such a ply of tinted glass has a green colouration. It mayhave a visible light transmission of less than 80% in 3.9 mm thickness(less than 87% in 2.1 mm thickness), whilst the transmitted energy mayadvantageously be less than 57% in 3.9 mm thickness (less than 70% in2.1 mm thickness).

A laminated glazing incorporating a ply glass tinted according to OptionC above as its “further ply” typically has a visible light transmissiongreater than 70%, possibly greater than 75%, and a transmitted energy of60% or less, and preferably 55% or less.

When a body-tinted interlayer material is used, the laminated glazing isoptimally provided in a thickness of 10 mm or less (yet greater than 3mm), however a thickness in the range from 4 mm to 8 mm is preferred.Furthermore, each ply comprised in the laminate is advantageously ofthickness in the range from 1.5 mm to 5 mm, although 2 mm to 3.5 mm ispreferred.

The sheet of interlayer material is typically a sheet of plastic, forexample polyvinylbutyral or other such suitable laminating material,which is tinted to have a visible light transmission of 35% or less at athickness of 0.76 mm. Preferably the interlayer material is tinted tohave a light transmission less than 30% and further preferably less than25%. Furthermore, the interlayer material typically absorbs infra-redradiation, for example when it comprises tin-doped indium oxide,lanthanum hexaboride or other such suitable infra-red radiationabsorbing material. The interlayer material may exhibit transmittedenergy of 25% or less, preferably 20% or less and most preferably 15% orless.

At least one ply of glass in the laminated glazing may be clear glasswhose composition may include, for example (by weight) 72.1% SiO₂, 1.1%Al₂O₃, 13.5% Na₂O, 0.6% K₂O, 8.5% CaO, 3.9% MgO, 0.2% SO₃ and optionallyup to 0.2% Fe₂O₃ (preferably less than 0.15%). Alternatively at leastone ply of glass may be tinted glass having a colourant portioncomprising 0.4 to 4.0% (by weight of the glass) of total iron(calculated as Fe₂O₃) and 0.05 to 1.6% by weight of ferrous oxide(calculated as FeO).

The total iron content of such a tinted ply of glass is preferably inthe range (% by weight) from 0.50 to 2.0, further preferably from 0.54to 1.5 and most preferably from 0.56 to 1.1. The ferrous oxide content(expressed as FeO) is preferably greater than 0.09%, further preferablygreater than 0.1% and most preferably greater than 0.12%.

A laminated glazing with a tinted interlayer preferably has a visiblelight transmission of 50% or less, further preferably 40% or less andmost preferably 35% or less. Advantageously, the laminated glazing has atransmitted energy of 30% or less, and further still of 20% or less.

Preferably laminated glazings in accordance with the invention,especially laminated glazings for use as roof glazings, exhibit avisible light transmission (LTA) of at least 15%, especially at least20%, and a total solar heat transmission, not more than 15%, preferablynot more than 10%, greater than their light transmission.

A glazing according to the first or second aspects of the invention maybe used as a roof glazing in a vehicle. It may be provided either as aconventional sun-roof glazing, or as a glazing that constitutessubstantially the entire roof area of a vehicle, which is often referredto as a “full-area roof light”. A glazing according to the second aspectof the invention may further be used as a vehicle windscreen whenappropriate visible light transmission requirements are met.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

For a better understanding, the present invention will now be moreparticularly described, by way of non-limiting example, with referenceto and as shown in the accompanying drawings wherein:

FIG. 1 is a cross sectional view through a vehicle glazing,

FIG. 2 is a cross sectional view through a laminated vehicle glazingaccording to the second aspect of the present invention in which the lowemissivity coating is provided on surface 4, and

FIG. 3 is a cross sectional view through a laminated vehicle glazingaccording to the third aspect of the present invention in which the lowemissivity coating is provided on surface 4.

DETAILED DESCRIPTION

Vehicle glazing 10 of FIG. 1 comprises glass pane 11 which has innersurface 12 and outer surface 13 (labeled with respect to a vehicle intowhich glazing 10 may be fitted). Inner surface 12 is provided withcoating 14; coating 14 may be located directly on inner surface 12, orit may be located on one or more further coating layers (not shown)which are located on inner surface 12. Such further coating layers maybe barrier layers to protect glazing 10 from species which may otherwisehave a tendency to migrate from coating 14 into glazing 10.

Glass pane 11 may be grey glass which has a base glass compositionincluding (by weight) 72.1% SiO₂, 1.1% Al₂O₃, 13.5% Na₂O, 0.6% K₂O, 8.5%CaO, 3.9% MgO and 0.2% SO₃, and a colourant portion comprising (byweight) 1.45% total iron (calculated as Fe₂O₃), 0.30% ferrous oxide(calculated as FeO), 230 ppm CO₃O₄, 210 ppm NiO and 19 ppmSe—hereinafter referred to as composition 1. Such a glass is currentlyavailable as GALAXSEE™ from Pilkington plc in the United Kingdom.

Coating 14 is a low emissivity coating. When coating 14 has anemissivity, ∈, as shown in Table 1 below, and is provided on glass pane11 (of composition 1 as described above), resultant glazing 10 exhibitsthe following properties at the thicknesses specified:

TABLE 1 Thickness of LT_(A) TE TSHT Ex. ε glazing 10 (%) (%) (%) a* b* 10.05 5 mm 9.8 5.2 19.3 −7.4 4.7 2 0.18 5 mm 11 9 24.5 −4.2 3.6 3 0.45 5mm 11 9.4 28.9 −4.4 2.7 4 — 5 mm 11.9 10.4 34.5 −4.2 2.4 5 0.05 6 mm 6.63.5 17.9 −7.1 4.6 6 0.18 6 mm 7.3 5.9 22.1 −4.4 3.6 7 0.45 6 mm 7.4 6.226.5 −4.6 2.8 8 — 6 mm 7.9 6.9 32 −4.4 2.5The total solar heat transmission (“TSHT”) of the glazing is the sum ofheat that is directly transmitted through the glazing (i.e. TE) and theheat that is absorbed by the glass of the glazing and subsequentlyre-radiated. The TSHT measurements were taken according to the Societyof Automotive Engineers' published standard SAE J1796 at 14 k.p.h.Parameters a* and b* are colour co-ordinates according to the CIELABsystem (measured at D65, 2° observer), and are used to define the colourof glazing 10.

Examples 4 and 8 are comparative examples which illustrate prior artversions of glazing 10 which are not provided with coating 14. Examples1 to 4 and 5 to 8 clearly show that the presence of a low emissivitycoating on a pane of the tinted glass in question has a minimal effecton the visible light transmission of the glazing (a maximum drop of 2.1percentage points is observed at 5 mm and 1.3 percentage points at 6 mm)whilst both the TE and TSHT values of the coated glazings are lower (andin some examples halved) compared to a corresponding un-coated glazing.

Alternatively glass pane 11 may be green glass which has the same baseglass composition as glass pane 11 described previously, and a colourantportion comprising (by weight) 1.57% total iron (calculated as Fe₂O₃),0.31% ferrous oxide (calculated as FeO), 115 ppm CO₃O₄, 0 ppm NiO and 5ppm Se—hereinafter referred to as composition 2. Such a glass iscurrently available as SUNDYM 435™, again from Pilkington plc in theUnited Kingdom. When coating 14 has an emissivity as shown in Table 2below, and is provided on glass pane 11 of composition 2, resultantglazing 10 exhibits the following properties at the thicknessesspecified:

TABLE 2 Thickness of LT_(A) TE TSHT Ex. ε glazing 10 (%) (%) (%) a* b* 90.05 5 mm 23 10.1 23.4 −15.3 2.8 10 0.18 5 mm 25.6 14 28.7 −11.5 1.3 110.45 5 mm 25.6 14.5 32.8 −11.8 0 12 — 5 mm 27.6 15.9 38.5 −11.6 −0.4 130.05 6 mm 18.2 7.8 21.6 −16 2.5 14 0.18 6 mm 20.2 10.5 25.9 −12.7 1.2 150.45 6 mm 20.3 10.8 30 −12.9 0 16 — 6 mm 21.8 11.9 35.6 −12.7 −0.4Examples 12 and 16 are further comparative examples illustrating priorart versions of glazing 10 which are not provided with coating 14.Examples 9 to 12 and 13 to 16 again clearly show that the presence of alow emissivity coating on a pane of the tinted glass in question has aminimal effect on the visible light transmission of the glazing (amaximum drop of 4.6 percentage points is observed at 5 mm and 3.6percentage points at 6 mm) whilst both the TE and TSHT values of thecoated glazings are lower (and in some examples a third lower) comparedto a corresponding un-coated glazing.

Further alternatively glass pane 11 may be green glass which has asimilar base glass composition as compositions 1 and 2 describedpreviously, and a colourant portion comprising (by weight) 1.30% totaliron (calculated as Fe₂O₃), 0.26% ferrous oxide (calculated as FeO), 128ppm CO₃O₄, 80 ppm NiO and 7 ppm Se—hereinafter referred to ascomposition 3. This composition is similar to composition 2 previouslydescribed, thus if this glass were to form glazing 10, the properties ofresultant glazing 10 would be similar to those measured and recorded inTable 2.

The cross sectional view of FIG. 2 illustrates that laminated vehicleglazing 20 comprises outer glass ply 21, inner glass ply 22 andinterlayer ply 24, in the form of a PVB sheet, which nominally has athickness of 0.76 mm. Outer glass ply 21 is tinted glass and inner glassply 22 is either tinted or clear glass (as described herein). When outerglass ply 21 alone is tinted, it is preferably of a composition chosenfrom composition 1, 2 or 3 described previously for glass pane 11; whenboth outer glass ply 21 and inner glass ply 22 are tinted, it is to thesame composition for each, again preferably chosen from composition 1, 2or 3 described previously for glass pane 11. For the avoidance of doubt,although outer glass ply 21 has been described as the glass ply that istinted in the case where only one glass ply of glazing 20 is tinted, itis however possible that inner glass ply 22 could be tinted instead ofouter glass ply 21.

In FIG. 2, surface 4 of glazing 20 (i.e. outer surface of inner glassply 22) is provided with coating 23, which, as for glazing 10, may bedirectly or indirectly located on said surface. Interlayer ply 24interleaves between outer glass ply 21 and inner glass ply 22,laminating the two glass plies together when all three aresimultaneously subjected to a lamination process in an autoclave. Thefollowing tables illustrate non-limiting examples of laminated glazing20 when it is comprised of various outer glass ply 21 and inner glassply 22 composition combinations, and when it is laminated with varioustypes of interlayer material. Thus, when coating 23 is a low emissivitycoating having an emissivity value as shown in the Tables, laminatedglazing 20 exhibits the properties listed at the glass thicknessesspecified, wherein:

Table 3 represents the case where outer glass ply 21 and inner glass ply22 are both tinted to the same colour according to composition 1 above,and interlayer ply 24 is either (a) clear PVB, (b) tinted PVB having 35%LT_(A), (c) tinted PVB having 18% LT_(A) or (d) an IR absorbing PVB asindicated (sheets of PVB are currently available from Solutia Inc., POBox 66760, St. Louis, Mo. 63166-6760 USA),

Table 4 is similar to Table 3 except in that outer glass ply 21 andinner glass ply 22 are both tinted to the same colour according tocomposition 2 above,

Table 5 represents the case where outer glass ply 21 is tinted accordingto composition 1 above, inner glass ply 22 is clear glass (typically asdescribed earlier), and interlayer ply 24 is either (a) clear PVB, (b)tinted PVB having 35% LT_(A), (c) tinted PVB having 18% LT_(A) or (d) anIR absorbing PVB as indicated, and

Table 6 is similar to Table 5 except in that outer glass ply 21 istinted according to composition 2 above.

TABLE 3 Thick- Thick- ness ness Inter- of outer of inner layer glassglass ply LT_(A) TE TSHT Ex. ply 21 ply 22 24 ε (%) (%) (%) a* b* 17 2.1 mm  2.1 mm a 0.05 13.6 7 20.8 −7.6 5.1 18 2.55 mm 2.55 mm a 0.059.4 4.9 19.1 −7.4 5 19  2.1 mm  2.1 mm a 0.18 15.2 12.3 27 −4 3.9 202.55 mm 2.55 mm a 0.18 10.5 8.5 24 −4.3 3.8 21  2.1 mm  2.1 mm a 0.4515.2 12.8 31.2 −4.3 2.8 22 2.55 mm 2.55 mm a 0.45 10.5 8.8 28.2 −4.5 2.923  2.1 mm  2.1 mm a — 16.4 14.1 36.8 −4 2.5 24 2.55 mm 2.55 mm a — 11.49.7 33.8 −4.4 2.8 25  3.1 mm  3.1 mm b 0.18 2.6 2.4 19.3 −6.9 3.3 26 3.1 mm  3.1 mm b — 2.8 2.9 29 −7 2.6 27  3.1 mm  3.1 mm c 0.18 1.4 1.718.8 −3.1 3.4 28  3.1 mm  3.1 mm c — 1.5 2.1 28.4 −3.2 2.9 29  3.1 mm 3.2 mm d 0.18 5.8 3.8 20.4 −5.1 4.8 30  3.1 mm  3.2 mm d — 6.3 4.1 29.8−5.2 3.9Examples 23, 24, 26, 28 and 30 are comparative examples illustratingprior art versions of laminated glazing 20 which do not include coating20. Examples 17 to 24 in particular show that the presence of a lowemissivity coating on an exposed surface of a laminated glazingaccording to the invention has a minimal effect on the visible lighttransmission of the glazing (a maximum drop of 2.8 percentage points isobserved for 2×2.1 mm plies and 2 percentage points for 2×2.55 mm plies)whilst both the TE and TSHT values of the coated glazings are lower (andin some examples halved) compared to a corresponding un-coated glazing.

TABLE 4 Thick- Thick- In- ness of ness of ter- outer inner layer glassglass ply LT_(A) TE TSHT Ex. ply 21 ply 22 24 ε (%) (%) (%) a* b* 31 2.1 mm  2.1 mm a 0.05 27.6 12.3 25.2 −14.6 3.3 32 2.55 mm 2.55 mm a0.05 22.3 9.7 23.1 −15.4 3.1 33  2.1 mm  2.1 mm a 0.18 30.8 17.6 31.4−10.5 1.8 34 2.55 mm 2.55 mm a 0.18 24.9 13.5 28.1 −11.8 1.6 35  2.1 mm 2.1 mm a 0.45 30.9 18.1 35.3 −10.8 0.4 36 2.55 mm 2.55 mm a 0.45 24.913.8 32.1 −12 0.3 37  2.1 mm  2.1 mm a — 33 20 41 −10.7 0 38 2.55 mm2.55 mm a — 27 15 37.7 −11.9 0 39  3.1 mm  3.1 mm b 0.18 8.1 4.4 20.9−15 1.6 40  3.1 mm  3.1 mm b — 8.7 5 30.5 −15.1 0.5 41  3.1 mm 2.55 mm c0.18 4.7 3.2 20 −8.8 2.3 42  3.1 mm 2.55 mm c — 5.1 3.8 29.6 −8.9 1.4 43 3.1 mm  3.1 mm d 0.18 18 8.2 24.1 −13.5 2.6 44  3.1 mm  3.1 mm d — 19.49 33.3 −13.7 1.1Examples 37, 38, 40, 42 and 44 are comparative examples illustratingprior art versions of laminated glazing 20 which do not include coating20. Examples 31 to 38 in particular show that the presence of a lowemissivity coating on an exposed surface of a laminated glazingaccording to the invention has a minimal effect on the visible lighttransmission of the glazing (a maximum drop of 5.4 percentage points isobserved for 2×2.1 mm plies and 4.7 percentage points for 2×2.55 mmplies) whilst both the TE and TSHT values of the coated glazings arelower (and in some examples over one third lower) compared to acorresponding un-coated glazing.

TABLE 5 Thick- Thick- ness ness of outer of inner Inter- glass glasslayer LT_(A) TE TSHT Ex. ply 21 ply 22 ply 24 ε (%) (%) (%) a* b* 45 3.1mm 2.3 mm a 0.05 20.5 10.5 23.4 −8.1 5.3 46 3.1 mm 2.3 mm a 0.18 22.7 1831.5 −4.1 3.8 47 3.1 mm 2.3 mm a 0.45 22.5 18.6 35.5 −4.3 2.7 48 3.1 mm2.3 mm a — 24.3 20.5 41.3 −4 2.3 49 3.1 mm 2.3 mm b 0.18 9.3 9 24.4 −8.63.5 50 3.1 mm 2.3 mm b — 10.1 10.6 34.4 −8.7 2.3 51 3.1 mm 2.3 mm c 0.184.9 6.3 22.3 −3.3 4.1 52 3.1 mm 2.3 mm c — 5.3 7.5 32.3 −3.3 3.2 53 3.1mm 2.3 mm d 0.18 21.1 13.8 28.3 −5 5.3 54 3.1 mm 2.3 mm d — 22.7 15 37.3−5 3.9Examples 48, 50, 52 and 54 are comparative examples illustrating priorart versions of laminated glazing 20 which do not include coating 20.Examples 45 to 48 in particular again show that the presence of a lowemissivity coating on an exposed surface of a laminated glazingaccording to the invention has a minimal effect on the visible lighttransmission of the glazing (a maximum drop of 3.8 percentage points isobserved when interlayer ply (a) is used) whilst both the TE and TSHTvalues of the coated glazings are lower (and in some examples halved)compared to a corresponding un-coated glazing.

Comparing examples 45 to 47 and comparative example 24, it will seemthat, using the invention with a tinted outer glass ply and a clearinner glass ply, a vehicle glazing with a much higher light transmission(LT_(A)>20%) may be achieved without significant loss of solarperformance over that achieved with two dark tinted panes without a lowemissivity coating. Indeed, when a low emissivity coating with anemissivity less than 0.2 is employed (examples 45 to 46), with a verymuch improved solar performance.

TABLE 6 Thick- Thick- ness ness of outer of inner Inter- glass glasslayer LT_(A) TE TSHT Ex. ply 21 ply 22 ply 24 ε (%) (%) (%) a* b* 552.55 mm 2.3 mm a 0.05 40.3 18.6 30 −12.9 4.1 56 2.55 mm 2.3 mm a 0.1845.1 28.9 40.1 −8 2.3 57 2.55 mm 2.3 mm a 0.45 45.1 29.7 43.8 −8.4 0.858 2.55 mm 2.3 mm a — 48.3 32.6 49.8 −8 0.3 59  3.1 mm 2.3 mm b 0.1816.5 11.4 26.4 −13.7 2.2 60  3.1 mm 2.3 mm b — 17.8 13.2 36.2 −13.9 0.861  3.1 mm 2.3 mm c 0.18 8.6 7.5 23.3 −6.9 3.2 62  3.1 mm 2.3 mm c — 9.28.8 33.2 −7 2.1 63  3.1 mm 2.3 mm d 0.18 37 19.4 33 −10.1 3.7 64  3.1 mm2.3 mm d — 40.4 21.2 41.8 −10.1 1.8Examples 58, 60, 62 and 64 are comparative examples illustrating priorart versions of laminated glazing 20 which do not include coating 23.Examples 55 to 58 in particular show that the presence of a lowemissivity coating on an exposed surface of a laminated glazingaccording to the invention has a minimal effect on the visible lighttransmission of the glazing (a maximum drop of 8 percentage points isobserved when interlayer ply (a) is used) whilst both the TE and TSHTvalues of the coated glazings are lower (and in some examples one thirdlower) compared to a corresponding un-coated glazing.

The examples of laminated glazings listed in Tables 3 to 6 are bestsuited for use as vehicle side glazings and roof glazings; none aresuitable for use as vehicle windscreens because none exhibit visiblelight transmission above 70% (in fact, all exhibit LT_(A) of less than50%). However, examples of laminated glazings which are suitable for useas vehicle windscreens are listed in Table 7 below. Outer glass ply 21and inner glass ply 22 of these glazings 20 may each be clear glass (forexample as described earlier), or green tinted glass having a similarbase glass composition as compositions 1, 2 and 3 described previouslyand a colourant portion comprising (by weight) 0.6% total iron(calculated as Fe₂O₃) and 0.13% ferrous oxide (calculated asFeO)—hereinafter referred to as composition 4—or 0.9% total iron(calculated as Fe₂O₃) and 0.19% ferrous oxide (calculated asFeO)—hereinafter referred to as composition 5. Interlayer ply 24 is inthe form of a clear PVB sheet which nominally has a thickness of 0.76mm. Again, surface 4 of glazing 20 (i.e. outer surface of inner glassply 22) is provided with coating 23 which, as for glazing 10, may bedirectly or indirectly located on said surface. When coating 23 is a lowemissivity coating having an emissivity as shown in Table 7, laminatedglazing 20 exhibits the properties listed in Table 7 at the glassthicknesses and compositions specified.

TABLE 7 Thickness & Thickness & Compo- Compo- sition sition P_(R) +Number (x) Number (x) DSHT of outer of inner LT_(A) TE DSHT (W m⁻² Ex.glass ply 21 glass ply 22 ε (%) (%) (%) K⁻¹) a* b* 65 2.1 mm 2.1 mm 0.1871.8 45.6 43.8 288.491 −7.1 3.9 (x = 4) (x = 4) 66 2.6 mm 2.1 mm — 70.943.6 42.8 347.53 −9 1.7 (x = 5) (x = 4) 67 2.1 mm 2.3 mm 0.18 76.1 56.654.5 349.23 −4.3 3.1 (x = 4) (x = clear) 68 2.1 mm 2.1 mm — 77.3 51.349.7 381.506 −7 1.5 (x = 4) (x = 4)Examples 66 and 68 are comparative examples which illustrate prior artversions of laminated glazing 20 which are not provided with coating 23.In Table 7, DSHT is measured at Air Mass 1.5 (simulating rays from thesun incident at an angle of 37° to the horizontal) over the wavelengthrange 300 to 2500 nm at 5 nm, 10 nm and 50 nm intervals. The powerradiated by the coating (“P_(R)”) on the glazing plus DSHT is calculatedfor the side of the glazing on which the coating is located. For thesefour examples, the ambient air temperature on the uncoated side of theglazing was measured to be 30° C., whilst that on the coated side of theglazing was measured to be 20° C. The solar power incident on theuncoated side of the glazing (representing sunlight incident on surface1 of laminated glazing installed as a vehicle windscreen) was measuredto have a value of 600 Watts per square meter per Kelvin (W m⁻² K⁻¹).Examples 65 and 66 illustrate laminated glazings which are suitable foruse as windscreens in USA (where the LT_(A) requirement is 70% orgreater) and examples 67 and 68 are suitable for use as windscreens inEurope (where the LT_(A) requirement is 75% or greater). In each case,it is clear that the overall value of the power radiated by the coatingplus DSHT (a measure of the heat energy actually entering a vehiclewhich is fitted with a laminated glazing according to the invention)decreases when a coating is present on the glazing compared to when acoating is absent.

FIG. 3 illustrates a laminated vehicle glazing 30 comprising outer glassply 31, inner glass ply 32 and interlayer ply 34, in the form of abody-tinted PVB sheet which nominally has a thickness of 0.76 mm(although it may be used in a thickness anywhere between 0.25 mm and 1.6mm). Both outer glass ply 31 and inner glass ply 32 are clear glass(although it is possible that one or both plies of glass could betinted, for example green tinted according to composition 4 or 5described previously). Surface 4 of glazing 30 is provided with coating33, which as for glazings 10 and 20, may be directly or indirectlylocated on said surface. Interlayer ply 34 comprises PVB which is tintedand includes an infra-red absorbing material, for example lanthanumhexaboride. At a thickness of 0.76 mm interlayer ply 34 alone exhibitsvisible light transmission of 20.6%, TE of 13.5%, TSHT of 37.1% and hasa* and b* values of −9.8 and 0.7 respectively when laminated with twopieces of clear glass as described earlier. The following table, Table8, illustrates non-limiting examples of laminated glazing 30 when itcomprises two 2.1 mm clear glass plies (for example according to acomposition hereinbefore described), an interlayer ply at two differentthicknesses and a low emissivity coating having an emissivity value asshown.

TABLE 8 Thickness of interlayer LT_(A) TE TSHT Ex. ply 34 ε (%) (%) (%)a* b* 69 0.76 mm 0.05 16.8 6.4 20.4 −13.4 3.6 70 0.76 mm 0.18 18.6 10.225.8 −10.4 2.5 71 0.76 mm 0.45 18.7 11.2 30.6 −10.5 1.3 72 0.76 mm —20.1 12.6 36.4 −10.4 0.9 73  0.4 mm 0.05 35 14.9 26.9 −12.1 4.3 74  0.4mm 0.18 39.1 24.8 37.2 −7.6 2.7 75  0.4 mm 0.45 39.1 26.3 42 −7.9 1.3 76 0.4 mm — 42.1 29.2 48.1 −7.6 0.8Examples 72 and 76 are comparative examples illustrating prior artversions of laminated glazing 30 which do not include coating 33.Examples 69 to 72 and 73 to 76 clearly show that the presence of a lowemissivity coating on an exposed surface of a laminated glazingaccording to the invention has a minimal effect on the visible lighttransmission of the glazing (a maximum drop of 3.3 percentage points isobserved when the interlayer ply is 0.76 mm thick and 7.1 percentagepoints when the interlayer ply is 0.4 mm thick) whilst both the TE andTSHT values of the coated glazings are lower (and in some exampleshalved) compared to a corresponding un-coated glazing.

What is claimed is:
 1. A vehicle glazing configured to be mounted in avehicle comprising: only one single pane of glass, wherein the singlepane of glass is a single pane of tinted glass, the single pane oftinted glass possessing an interior surface which faces a vehicleinterior when the vehicle glazing is mounted in a vehicle, the singlepane of tinted glass having a nickel content, calculated as NiO, morethan 55 ppm, a colourant portion including 1.0 to 1.8% (by weight of theglass) of total iron (calculated as Fe₂O₃), 100 to 270 ppm by weight ofcobalt oxide (calculated as Co₃O₄) and selenium (calculated as Se) in anamount less than 20 ppm by weight, and a low emissivity coating directlycontacting the interior surface of the pane, and the glazing has avisible light transmission of 28% or less.
 2. A vehicle glazing asclaimed in claim 1, wherein the low emissivity coating has an emissivityin the range from 0.05 to 0.45 determined according to EN
 12898. 3. Avehicle glazing as claimed in claim 1, wherein the low emissivitycoating includes a transparent conductive oxide.
 4. A vehicle glazing asclaimed in claim 3, wherein the low emissivity coating further includesa dopant.
 5. A vehicle glazing as claimed in claim 1, wherein the paneof tinted glass is toughened glass.
 6. A vehicle glazing as claimed inclaim 1, wherein the pane of tinted glass has a thickness in the rangefrom 1.5 mm to 8 mm.
 7. A vehicle glazing as claimed in claim 1, whereinthe pane of tinted glass includes 0.05 to 1.6% by weight of ferrousoxide (calculated as FeO).
 8. A vehicle glazing as claimed in claim 1,wherein the pane of tinted glass includes up to 500 ppm by weight ofnickel oxide (calculated as NiO).
 9. A vehicle glazing as claimed inclaim 1, having a transmitted energy of 30% or less.
 10. A vehicleglazing as claimed in claim 1, wherein the glazing is a roof glazing.11. A vehicle glazing configured to be mounted in a vehicle, the vehicleglazing comprising: only one single pane of glass, wherein the singlepane of glass is a single pane of body-tinted glass; the single pane ofbody-tinted glass possessing an interior surface which faces a vehicleinterior when the vehicle glazing is mounted in a vehicle; the singlepane of body-tinted glass having a nickel content, calculated as NiO,more than 55 ppm, a colourant portion including 1.3 to 1.6% (by weightof the glass) of total iron (calculated as Fe₂O₃), 150 to 230 ppm byweight of cobalt oxide (calculated as Co₃O₄) and selenium, wherein theselenium (calculated as Se) is present in an amount less than 20 ppm byweight; a metal oxide low emissivity coating directly contacting theinterior surface of the pane; and the vehicle glazing possessing avisible light transmission of 36% or less measured according to C.I.E.Illuminant A.
 12. A vehicle glazing as claimed in claim 11, wherein thelow emissivity coating has an emissivity in the range from 0.05 to 0.45determined according to EN
 12898. 13. A vehicle glazing as claimed inclaim 11, wherein the low emissivity coating includes a transparentconductive oxide.
 14. A vehicle glazing as claimed in claim 11, whereinthe low emissivity coating includes a dopant.
 15. A vehicle glazing asclaimed in claim 11, wherein the pane of tinted glass is toughenedglass.
 16. A vehicle glazing as claimed in claim 11, wherein the pane oftinted glass includes a nickel content (calculated as NiO) more than 100ppm and up to 500 ppm.
 17. A vehicle glazing as claimed in claim 16,wherein the glazing has a transmitted energy of 30% or less measured atAir Mass 2, ISO
 9050. 18. A vehicle glazing as claimed in claim 16,wherein the glazing has a transmitted energy of 20% or less measured atAir Mass 2, ISO
 9050. 19. A vehicle glazing as claimed in claim 11,wherein the glazing has a transmitted energy of 30% or less measured atAir Mass 2, ISO
 9050. 20. A vehicle glazing as claimed in claim 11,wherein the glazing has a transmitted energy of 20% or less measured atAir Mass 2, ISO 9050.